Microsopic Simulation of Thermally-Induced 2nd Order Eigenstresses in AlSi-Alloys: Microsopic Simulation of Thermally-Induced 2nd Order Eigenstresses in AlSi-Alloys

Due to the different coefficients of thermal expansion of aluminium and silicon, high residual stresses of second order occur in Al-Si alloys depending on the cooling rate during the molding process. In products as for example crank cases made of Al-Si alloys these residual stresses may cause microcracks. In the work at hand measurements of the eigenstresses in the single phases (i.e. residual stresses of second kind) performed via neutron diffractometry are compared to numerical simulations for a specific cooling rate. To this end a three-phase model is presented, which considers the α aluminium, the eutectic aluminium, and the silicon particles. The presented model is able to predict the residual stresses in the single phases within an elastoplastic framework. The simulation of tensile loadings of these structures are compared to experiments. The numerical computations are carried on stochastic geometry models by using a fast solver [1] for the Lippmann-Schwinger integral equation, which is based on the fast Fourier transformation. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)